The fair value of the Company’s financial assets and liabilities measured on a recurring basis were as follows:

	March 31, 2020											December 31, 2019
(U.S. Dollars, in thousands)	Level 1		Level 2			Level 3			Total			Total
Assets
Bone Biologics equity securities	$	—	$	—		$	—		$	—		$	219
Total	$	—	$	—		$	—		$	—		$	219
Liabilities
Contingent consideration	$	—	$	—		$	(33,700	)	$	(33,700	)	$	(42,700	)
Deferred compensation plan		—		(1,235	)		—			(1,235	)		(1,255	)
Total	$	—	$	(1,235	)	$	(33,700	)	$	(34,935	)	$	(43,955	)

The Company recognized a contingent consideration obligation in connection with the acquisition of Spinal Kinetics in 2018. The contingent consideration consists of potential future milestone payments of up to $60.0 million in cash. The milestone payments included (i) up to $15.0 million upon U.S. Food and Drug Administration (“FDA”) approval of the M6-C artificial cervical disc (the “FDA Milestone”) and (ii) revenue-based milestone payments of up to $45.0 million in connection with future sales of the acquired artificial discs. Milestones must be achieved within five years of April 30, 2018 to trigger applicable payments. In February 2019, the FDA Milestone was achieved and paid.

The estimated fair value of the remaining contingent consideration was $33.7 million as of March 31, 2020. The estimated fair value reflects assumptions made by management as of March 31, 2020, including the impact of COVID-19 on significant unobservable assumptions, such as the expected timing and volume of elective procedures and the impact of these procedures on future revenues. However, as the impact of COVID-19 on the Company’s business is highly uncertain and difficult to predict, and as information surrounding the pandemic is rapidly evolving, the actual amount ultimately paid could be higher or lower than the fair value of the remaining contingent consideration. As of March 31, 2020, the Company has classified the full balance of the remaining $33.7 million within other long-term liabilities. Any changes in fair value are recorded as an operating expense and included within acquisition-related amortization and remeasurement.

The following table provides a reconciliation of the beginning and ending balances for the contingent consideration measured at fair value using significant unobservable inputs (Level 3):

(U.S. Dollars, in thousands)	2020			2019
Contingent consideration at January 1	$	42,700		$	28,560
Increase (decrease) in fair value recognized in acquisition-related amortization and remeasurement		(9,000	)		5,400
Payment made		—			(15,000	)
Contingent consideration at March 31	$	33,700		$	18,960

The $9.0 million decrease in fair value in 2020 is primarily attributable to a change in management’s forecast of future net sales of artificial discs because of uncertainty in the market and the economy from the impact of COVID-19.

The Company estimated the fair value of the remaining potential future revenue-based milestone payments using a Monte Carlo simulation and a discounted cash flow model. This fair value measurement is based on significant inputs that are unobservable in the market, and thus represents a Level 3 measurement. The key assumptions in applying the valuation model include the Company’s forecasted future revenues for Spinal Kinetics products, the expected timing of payment, applicable discount rates applied, and assumptions for potential volatility of the Company’s forecasted revenue. Significant changes in these assumptions could result in a significantly higher or lower fair value.

The following table provides a range of key assumptions used within the valuation as of March 31, 2020.

(U.S. Dollars, in thousands)	Fair Value as of March 31, 2020		Valuation Technique	Unobservable inputs	Range
Contingent consideration	$	33,700	Discounted cash flow	Revenue discount rate	5.0% - 5.3%
				Payment discount rate	6.7% - 7.0%
				Projected year of payment	2021 - 2022

Until October of 2019, the Company held a debt security and a related warrant to purchase common stock of eNeura, Inc. (“eNeura”), a privately held medical technology company that is developing devices for the treatment of migraines. On October 25, 2019, the Company and eNeura settled the debt security for a $4.0 million cash payment and agreed to transfer the warrant to eNeura.

The following table provides a reconciliation of the beginning and ending balances for the eNeura debt security and warrant measured and reflected in the condensed consolidated balance sheets at fair value using significant unobservable inputs (Level 3) prior to the settlement discussed above:

(U.S. Dollars, in thousands)	2020		2019
eNeura debt security and Warrant at January 1	$	—	$	17,820
Gains or losses recorded for the period
Recognized in other comprehensive income (loss)		—		(2,593	)
Change in classification of debt security to held to maturity		—		(15,227	)
Issuance of Warrant as consideration for extension		—		491
eNeura debt security and Warrant at March 31	$	—	$	491